Commutator motor brush holder



Dec. 25, 1951 G. GIAMBONINI COBIHMUTA TOR MOTOR BRUSH HOLDER Filed Aug. 28, 1950 (rumo Gmnaomm AT-roRNEYS Patented Dec. 25, 1951 COMMUTATOR Moronv BRUSH HOLDER Guido Giambonini, Bellinzona, Switzerland Application August 28, 1950, Serial No. 181,873 In Switzerland September 1, 1949 4 Claims. (Cl. 171-324) My present invention relates to improvements in means incorporated in commutator motor brush holders for ensuring a positive contact between the carbon brushes and the commutator face and a positive power supply to .the commutator; and the objects of my invention are to obtain an improved power lead, a reduction in collector wear, and the use of extremely simple carbon brushes, in particular brushes which do not comprise any metallic fittings.

My invention is particularly applicable to single-phase alternating-current commutator motors and electric-traction motors in general, and affords convenient simplifications and advantages in the service of such motors and lowered operating costs.

Two forms of invention are illustrated in the accompanying drawing in which:

Fig. 1 is a side view, partly in section, of a modern brush holder embodying one form of invention,

Fig. la is a top plan view as indicated by the arrows AA in Fig. 1,

Fig. 2 is a front view of a modified contact cylinder comprising a retaining rib,

Fig. 3 shows three difierent carbon brush structures a, b and c which may be used in connection with my invention,

Fig. 4 shows a side view of an older type brush holder embodying a second form of invention, in which holders sometimes riders or spacers are used between loading finger and brush, and

Fig. 5 is a front view of a second modification of the contact cylinder provided by my present invention, which cylinder here has no retaining rib.

The openings of a conventional brush holder g are provided with recesses e (Fig. 1) in the rocking range of a loading bow d. The loading finger normally used for depressing the carbon brush with the aid of a pressure element, is replaced by the loading bow d. The latter is secured to an arm 9' which is pivoted to holder g and engaged by a spring j which tends to rock the arm anticlockwise so as to bear down onto a contact cylinder lodged freely in the hollow provided on the head of brush t.

The said cylinder comprises an outside metallic sleeve 2 to which is secured a flexible power lead I which is disposed either on one side (as in Fig. l) or on both sides of sleeve 2. That portion of lead I which is subjected to wear and tear is protected by a spring sleeve .9. The sleeve 2 transmits the pressure and current to the carbon brush t. The bow d through a suitable opening (not shown) in sleeve e bears on a fragmentary core h made of an elastic and insulating material which dampens vibrations. A metallic tube m bonded to the core h is provided where required, and serves for distributing the pressure of how it uniformly on the core 71. and for reducing the frictional losses between the rocking how (1 and the contact cylinder which moves in direction of the brushes t which bear radially onto the commutator C. The bow it bears on tube in through an appropriate sliding surface 10.

In the modification shown in Fig. 2, a retaining rib r is provided in the sleeve 2 of the contact cylinder, and a loop 1 (Fig. l) is fixed to the free end portion of bow d and passed through a slot in sleeve 2 on one side of rib r so that the latter holds the bow d in proper position with respect to tube m during the useful life of the brushes t.

The positive but loose seating of the contact cylinder in the V-guide of the brush head, and the property of the bow d to transmit the pressure through a suitable sliding face p onto said cylinder, permits of making more efficient use of the brushes and at the same time facilitates the motor service.

In shops using a plurality of different brush sizes, my invention affords a further advantage in that one size of contact cylinder may be used therefor.

Different brush structures t, t and t", as shown at a, b, c in Fig. 3, may be used in my invention for one and the same size of contact cylinder, such as plural-part brushes (a), laminated brushes (b), and one-piece brushes (0).

In motors of older types, which are provided with substantially upright, short and sturdy pressure fingers which bear on the brushes via a spacer, the use of a contact cylinder as disclosed by my present invention is made possible by the provision of a link it as shown in Fig. 4 which illustrates a second form of invention. In this case, the sleeve 2 of the contact cylinder is provided with a single slot, and not as in the modification of Fig. '2 with a rib r. In this form also, all the components are secured against becoming disengaged.

What I claim as new and desire to secure by Letters Patent, is:

1. A pressure and current transmitting device for brushes of an electric commutator motor and the like having brush holders and brushes slidable therein and wherein said brushes are provided with a slot in the brush head comprising a hollow contact sleeve loosely seated in said slot in said brush head, said sleeve extending over a substantial portion of said brush head, an insulating, elastic, vibration damping insert in the interior of said hollow sleeve, a pressure member pivotally mounted on said brush holder, a slide surface on said pressure member, said slide surface contacting and coacting with said insert whereby said contact sleeve is freely self-adjustable in accordance with the degree of wear of the brush.

2. A pressure and current transmitting device as claimed in claim 1, and wherein the elastic, vibration-damping insert extends over substantially the entire length of the contact sleeve and a pressure distributing member of substantially the same length is inserted in saidsleeve incontact with said insert, said pressure member acting on said pressure distributing member, the pres- 7 sure force being transmitted over the entire length.

3. A pressure and current transmitting device as claimed in claim 2, and including between the contact sleeve and the pressure member, a loose connection which, without preventing free adjustment of the contact sleeve in the brush head, prevents the contact sleeve from falling onto the commutator when the latter is impaired due to any disruption of the brushes.

4.- A pressure and current transmitting device as claimed in claim 3, said elastic, vibrationdamping insert being positioned in the manner of a sector of a circle, in the operative range of the pressure member, and the pressure distributing member being mounted in the contact sleeve, said sleeve having a slot through which extends the portion of the pressure member provided with the sliding surface and which acts on the pressure distributing member.

GUIDO GIAMBONINI.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS Germany June 7, 1938 

